Spectrofluorimetric and spectrophotometric methods for the determination of gemifloxacin in bulk and tablets

Abstract

Two sensitive, selective, accurate spectrofluorimetric and spectrophotometric methods have been developed for the determination of gemifloxacin (GMFX) in bulk and tablets. The first method (A) was based on a reaction between gemifloxacin with zirconium (IV) in presence of acetate buffer of pH 6.0 to give highly fluorescent derivatives. The reaction was monitored spectrofluorimetrically by measuring the emission of the reaction product at 397 nm and excitation maxima at 265 nm. Various factors affecting the relative fluorescence intensity of the resulting chelate were studied and optimized. Beer's law was obeyed in the concentration range 0.5–4.0 μg/mL with a correlation coefficient of 0.9997. The second method (B) was based on formation of ternary complex between palladium (II), eosin and GMFX in the presence of methyl cellulose as surfactant and acetate-HCl buffer pH of 4.0. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 530 nm. Beer's law was obeyed in the concentration range 2.0–22 μg/mL with a correlation coefficient of 0.9995. The composition of the complex, studied by the limiting logarithmic method shows that the molar ratio GMFX: Pd (II): eosin is 1:1:1. The detection and quantification limits were also calculated. The proposed methods were successfully applied for the determination of gemifloxacin in its pharmaceutical product with mean percentage recoveries of 98.9%.